Problem with class member layout (footprint)

So, I'm working on this scripting engine...
Now, here are a few classes I have; they're all defined in an overlaying Script class:

Code:

class Parser{
protected:

	// methods...
};



class CppClass: public Parser{
private:

	class Operator{
	private:

		unsigned int udw_return_flags;
		unsigned int udw_arg_flags;
		Script::Operator *pO_op;

	public:

		Operator(void);
	};

	unsigned int udw_flags;
	String S_name;
	List<Script::CppBaseFunction> LtCBF_methods;
	List<Script::CppBaseFunction> LtCBF_statics;
	List<Script::CppClass::Operator> LtO_operators;
	List<Script::Variable> LtV_variables;

	// methods...

protected:

	Script::Variable V_return;
	List<Script::Variable *> *pLtpV_args;
	List<Script::Variable> LtV_statics;
	Script *pS_engine;

	// methods...

public:

	// methods...

	friend class Script;
};



class Block{
protected:

	unsigned int udw_flags;
	Script::Clause *pC_parent;

	// methods...

public:

	List<Script::Variable *> LtpV_variables;

	// methods...

	friend class Script;
};



class Variable: public Script::Block{
private:

	Script::Block *pB_pointer;
	Script::Clause *pC_parent_real;
	Script::Class *pC_class;
	String S_name;
	double d_index;

	// methods...

public:

	double d_number;
	String S_string;

	// methods...

	friend class CppClass;
	friend class Script;
};

The problem is, when I do the following, I get two different numbers output - which sucks, since I'm using the udw_flag member to determine whether it's a class, variable, etc...

Code:

Script::Variable V_test;
V_test.udw_flags = 777; // some random number

Script::CppClass *pCC_test = (Script::Variable *)&V_test;

printf("\nflags: %u", V_test.udw_flags);
printf("\nflags: %u", pCC_test->udw_flags);

So, I take it the compiler rearranges the members and/or in some other way changes the footprint of the classes...
Can I prevent this with some command? (I'm using VC++ 7.0 by the way.)

Help, pretty please?

What are you trying to do? Why are you casting there? CppClass and Variable are two different classes, so if you have a Variable, use its udw_flags, and if you have a CppClass use its udw_flags.

Or have them both derive from the same base class and put the flags in that base class.

I don't understand why you'd want to convert one type to the other.

I'm not trying to convert from one class to the other. I just have a list of lots of Script::Variable pointers that can infact be pointing to a Script::CppClass instance... I know I could make them both inherit from a base class with udw_flags defined in it - and I have implemented that as of yesterday - but still, I'd like to know if there's anything I can do to prevent this stuff...

There is no reason you should ever have a Script::Variable pointer pointing to a Script::CppClass instance. They are two completely different, unrelated classes. I don't even think that is legal, you are forcing the compiler to accept it with the C style cast, but it will yield undefined behavior. It's like having an int pointer pointing to a string.

Again, what are you trying to accomplish by storing CppClass addresses in a Variable pointer? Are you trying to make a list of Variables that could be different things, including possibly a CppClass? If so, then Variable would be a base class (either directly or indirectly) of CppClass, or they would share a common base class. There are other ways to accomplish that, but fixing your inheritance hierarchy is probably the best bet.